Collapsible ladder



Oct. 30, 1962 c, w, GILES 3,061,042

COLLAPSIBLE LADDER Filed May 25. 1960 6 Sheets-Sheet 1 r 1 r n 0 r! 4 4 6d I as i '6 60- l i i I 0 III 42 1 7 40 I J 46 T- r I 1 Z mmvrom 81 77 UHARLES W E'ILES.

Q 70 BY ATTY.

Oct, 30, 1962 c. w. GILES 3,061,042

COLLAPSIBLE LADDER Filed May 25, 1960 6 Sheets-Sheet 2 /55 m5 m4" m TEE- #6 L7 AHLES I/I/ GILES.

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Oct. 30, 1962 c. w. GILES COLLAPSIBLE LADDER 6 Sheets-Sheet 3 Filed May 25. 1960 LL 2 MI fIE-lEl-A- INVENTOR:

" [HARLEE I IZ FILES- Oct. 30, 1962 c. w. GILES COLLAPSIBLE LADDER 6 Sheets-Sheet 6 Filed May 25, 1960 9 MM 4 24 0 4 a 5m 0 BM 2 K. 4 4 5 w 4 3 ?J m 3 s m .4 5 0 M /I\|\ 6 a m Mm 4 4\ 5 6 1 an a m 4 4 4 INVENTOR: I IZ firms.

CHARLES BY ATTIC United States Patent C) 3,061,042 COLLAPSIBLE LADDER Charles W. Giles, 2841 Navarre Ave, Oregon, 01110 Filed May 25, 1960, Ser. No. 31,681 24 Claims. (Cl. 182-195) This invention relates to ladders. More particularly it relates to telescoping ladders comprised of cast parts and especially adapted for use as a boarding ladder for small boats.

With the growth of the use of small boating and with the attendant growth of water-skiing as a popular sport, many ladders which may be hung over the side or transom of an outboard or inboard boat to enable a swimmer or skier to easily enter such a boat, have recently become avaiable. These ladders are primarily of the fixed length rigid type and are generally merely hung over a gunwale against the outer shell of the boat. Because these ladders are rigid and non-collapsible and are generally stowed on board the vessel where storage space is at a premium, they are generally very short so that they may be conveniently handled and stowed. Other ladders of the rope type may be longer but are undesirable for reasons soon to be described.

Limiting this critique temporarily to the fixed type of ladder, unless they are used on a boat which has a very low freeboard it is a very difiicult, and often dangerous, operation for the person boarding the boat to use such a ladder. This is because the short length of the ladder puts the lowest rung or tread of the ladder a very short distance below the surface of the water and the boarder is required to assume a doubled-up position to place his feet on the bottom rung of such 'a ladder. He must then straighten up to climb the ladder and climb over the gunwale or transom; while he is doubled up and while he is straightening himself the boarder is in such a position that it is very dilficult for him to control his movements. The untenable physical position of the boarder is especially precarious if the water is choppy to rough and if the boat is pitching and/ or rolling since there is a great danger that the boarder will either be thrown off the ladder, thrown against the side of the boat and be injured, or lose his balance as he is crossing the gunwale and fall forward onto the boat. The problem is aggravated if the boarder is a physically tired swimmer or skier. While there is no way to absolutely assure that such a person will never suffer such injuries, the possibilities of such an injury would be greatly reduced if the boarder could climb the ladder without assuming the precarious crouched position described, or if he could safely assume a vertical position on the ladder so that he could gain control of his situation before climbing over the gunwale. Such increased safety would be available if the ladder were longer with the treads or rungs a convenient and comfortable distance below the surface of the water, but as we have seen, such a ladder would be too long to be readily stowed aboard the vessel.

As mentioned previously, an alternate to the short rigid ladder is the rope type ladder which may be of almost any length and still be readily stowable but which is not rigid. Because of the lack of rigidity of such ladders, if the boat is pitching and/ or rolling, it is diflicult for the boarder to maintain his balance and the same hazardous conditions are imposed on him.

It is a primary object of this invention to provide a telescoping ladder which is rigid when extended.

It is another primary object of this invention to provide a telescoping ladder of any length desirable.

It is an object of this invention to provide a telescoping ladder which may be positively locked into position on a gunwale or transom of a small boat.

" ice Another object is to provide a long rigid ladder which may be telescoped for convenient stowage.

Another object is to provide a telescoping ladder of cast metal sections requiring a minimum of finishing, which may be snapped together and which has positive slidable locking between its adjacent telescoping members.

Another object is to provide a telescoping metal ladder which may be dis-assembled readily for maintenance and painting if desired.

Another object is to provide a ladder for four-point cooperation with a doubly curved surface such as the shell of a small boat.

Another object is to provide a small boat boarding ladder with adjustable stand-off members to control the angle at which the ladder extends from the side of the vessel.

Still another object is to provide positive locking hangers for a boarding ladder which may be attached to a vertical or horizontal surface adjacent a boats gunwale or on its transom.

Generally, the ladder of this invention includes a plurality of planar treads or step elements. The treads may be comprised of one-piece members, or a pair 'of identical tread members may be interlocked to form a single planar tread. Also the invention includes a plurality of essentially identical risers or step connecting elements which may be arranged in pairs, one at each end of a tread element. The risers are connected to the tread element to form a U-shaped ladder subsection which is ultimately movable or telescoped with respect to adjacent U-shaped subsections in the finished ladder. The risers and the treads of each subsection carry flanges, lugs, and notches for fitting together in positive interlocking attachment and for guiding and interlocking adjacent U- shaped subsections in sliding motion when the assembled ladder is extended and compacted according to its telescoping principles. Each individual riser also incorporates means for further guiding of adjacent subsections and for interlocking with the risers of the adjacent subsection.

The ladder of this invention may also include a pair of extensions for the top or uppermost risers. The individual members of this pair of extensions may have lugs, notches, flanges, and slots present in their construction for slidable, positively interlocking attachment with the top pair of risers and for such attachment with standoff arms which may also be found as a part of the members comprising this invention. The top riser extensions may also include hanging hooks or arms for supporting the ladder on whatever structure it is applied to. The apparatus of the ladder of this invention may further include a rung extending between the riser extensions serving as a hand-hold for the person using the ladder.

These and other objects and features of this invention and the manner of attaining them will become more apparent and the invention itself will be best understood by reference to the following description of embodiments of this invention taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a front elevational View of a first embodiment of a tour step ladder according to this invention shown in its fully extended position;

FIFIG. 2 is a top plan view of the ladder shown in G.

FIG. 3 is a side elevational view of the ladder shown in FIG. 1;

FIG. 4 is an enlarged sectional elevational view as may be taken along line IV-IV of FIG. 3 of the corner of a step section;

FIG. 5 is an enlarged sectional plan view as may be taken along line VV of FIG. 1;

FIG. 6 is an enlarged perspective exploded view show- 1 3 ring the ladder of FIGS. 1-3 of the first embodiment of this invention;

FIG. 7 is a plan view of a position in the method of connecting adjacent risers of this first embodiment of this invention shown in FIGS. 1-6 for their interlocking sliding relationship between each other;

FIG. 8 is a front elevational view of a second embodiment of a three step ladder according to this invention in its extended position;

FIG. 9 is a side elevational view of the ladder shown in FIG. 8;

FIG. 10 is a top plan view of the ladder shown in FIG. 8; c

FIG. 111 is an enlarged sectional plan View as may be taken along line XIX of FIG. 8 showing the installation of a retractable stand-01f means under the tread of a top step section;

FIG. 12 is an enlarged perspective view of one end of a tread as may be used in the second embodiment of this invention as shown in FIGS. 8 and 9;

FIG. 13 is an enlarged sectional elevational view as may be taken along line XIII-XIII of FIG. 9 showing the interlocking connection between the trends and risers of the second embodiment of the ladder of this invention shown in FIGS. 8 and 9;

FIG. 14 is an enlarged elevational and partially cutaway view of the connection between the treads and risers of the ladder of the second embodiment of this invention as may be taken along line XIV-XIV of FIG. 13;

FIG. 15 is a view similar to FIG. 14 showing a stage of the installation of the spring loaded retaining pins in the joint between the treads and risers of this second embodiment of the ladder of this invention;

FIG. 16 is a perspective view of a retaining pin used in conjunction with the second embodiment of this invention as shown in FIGS. 14 and 15;

FIG. 17 is a side elevational view of a third embodiment of this invention showing in full lines a three step ladder installed, in its extended position, on the vertical face of the transom of a small boat;

FIG. 18 is a front elevational view of this third embodiment of a ladder according to this invention mounted on the transom of a boat in the manner depicted in FIG. 17 with a part broken away;

FIG. 19 is a partial elevational view showing the third embodimentof this invention mounted on the top of the gunwale of a small boat with the adjustable stand-01f means bearing against the side shell of the boat;

a FIG. 119-A is an enlarged sectional view as may be taken along line XIX-AXIX-A of FIG. 19, showing the connection of the stand-off arm, top riser rung, top riser, and top riser extension of the third embodiment of this invention;

FIG. 20 is a side elevational view of an alternate form of the top riser extension which may be used with the third embodiment of this invention;

FIG. 21 is an enlarged sectional elevational view of the positive locking hanger hook and receptacle as may be taken along line XXIXXI of FIG. 18;

FIG. 22 is a side elevational view showing a fourth embodiment of a four step ladder according to this invention in an extended position and installed on the transom of a small boat;

FIG. 23 is a front elevational view of the fourth embodiment of the ladder of this invention as installed according to FIG. 22;

FIG. 24 is a perspective exploded view of a part of the fourth embodiment of this invention shown in FIGS. 22 and 23, showing a top riser, a top riser extension, a standoff arm, and part of the hand-hold bar; a

FIG. 25 is an enlarged plan view showing the first position in the process of assembling the top riser and the top riser extension of the fourth embodiment of this invention shown in FIGS. 22-24;

FIG. 26 is a further enlarged sectional view as may be taken along line XXVI-XXVI of FIG. 25 showing the eared stub-shaft as first inserted into its cooperating slot in the top riser extension;

FIG. 27 is an enlarged sectional view as may be taken along line XXVIIXXVII in FIG. 25 with the top riser rotated into alignment with the top riser extension showing the ears of the stub-shaft engaging the slot flanges of the top riser extension;

FIG. 28 is an enlarged sectional view, as may be taken along line XXVIIL-XVIII of FIG. 25 after the top riser has been rotated clockwise into cooperation with the top riser extension;

FIG. 29 is an enlarged vertical cross-sectional view of the assembled parts depicted in FIG. 24;

FIG. 30 is a top plan view of one of the tread members of the fourth embodiment of this invention of FIGS. 22-23 showing in dashed lines the cooperating second identical tread member comprising the entire tread unit;

FIG. 31 is a side elevational view of a tread member shown in FIG. 30;

FIG. 32 is an end view of one of the cooperating tread members, according to the fourth embodiment of this invention, as may be taken along line XXXIIXXXII of FIG. 31;

FIG. 33 is an enlarged top plan view of cooperating tread members and a section of a riser as may be taken along line XXXIII-XXXIII in FIG. 23;

FIG. 34 is an enlarged side elevational view of a pair of engaged tread members according to the fourth embodiment of this invention showing the tread unit in complete and partial engagement with its two cooperating risers, respectively; and

FIG. 35 is a further enlarged cross-sectional view of a pair of engaged tread members as may be taken along line XXXV-XXXV of FIG. 33.

Four embodiments of this invention of varying complexity are shown in the drawings and are described hereafter. In order to explain the apparatus of the ladder of the present invention, reference will now be had in detail to these specific forms of this invention. To aid in following the further description of this telescoping cast ladder having positive interlocking snap-together assembly, for use on small boats, it will be divided into the following chapters and sub-chapters:

I-First Embodiment of the Ladder (39):

A-Treads (40-53) BRisers (60-86) C--Assembling the Ladder"; (90-94) II-Second Embodiment of the Ladder ATr (101-125) BRisers o (-167) CAssembling the Ladder (-174) HIThird Embodiment of the Ladder AGeneral Components:

1. Treads (200-225) 2. Risers (181-196) BTop U-Shaped Subassembly:

1. Top Riser (230-237) 1. Treads (401-436) 2. Risers (440-442) BTop Riser Subassembly:

1. Top Riser Extensions (450-469) 2. Stand-oft Arms (470-478) 3. Spreader Rung (480) 4. Assembly of Top Subassembly CAssembly of the Ladder D-Hanger Bars (490 494) (The numbers in parenthesis following each chapter, sub-chapter, and sub-chapter divisions are the reference characters which appear first in description under such divisions.)

I-FIRST EMBODIMENT OF THE LADDER Referring to FIGS. 1 through 7, there is shown the simplest form of the four ladders described to illustrate this invention. The first embodiment of this ladder 39, also true of the other embodiments described later, is comprised of two basic elements used repeatedly throughout the device; these elements are the treads 40 and the risers 60.

Since one of the objects of this invention is to provide a ladder of cast components, the treads 40 of the ladder may be cast of any castable material, but, considering the uses which this ladder may be put to, the most preferable material is age-hardening aluminum.

The treads 40 of this form 39 of the invention are substantially planar in form and are of essentially rectangular configuration being symmetrical about their longitudinal and transverse center lines. From the ends 41 of the treads 40 there may extend projections or lugs 42. These lugs 42 should be at the corners of the tread 4t) and may thus form a recess or notch 43 in the ends 41 of the tread extending across the thickness of the tread between the projections 42. Located in the transverse or back face 44 of the recesses 43 there may be drilled and tapped holes 45 extending into, but not necessarily through, the body 46 of the tread between the upper face 47 and lower face 48 of the tread 40 (see also FIG. 4). The inner longitudinal surfaces 49 and 56 forming the ends 51 of the recess 43 may be, and preferably are, parallel to each other.

Located in the upper surface 47 of the tread 40 there may be a pattern of grooves 52 to provide traction for the person using the ladder 39. This is especially critical if the ladder 39 is aflixed to the side of a boat (as shown in FIGS. 17, 18, 22, and 23) and the person using the ladder 39 is barefoot. In the form the ladder 39 shown in FIG. 6, the grooves 52 run longitudinally of the tread 40.

As may be seen in FIG. 1, because of the method of construction and assembly of the ladder 39, it is necessary that the treads 40 be of varying length, as measured between the back faces 44 of the recesses 43 at the ends of the treads 40. The difference in length between each of the treads 40 of this embodiment 39 of the ladder is approximately equal to twice the thickness of the Users 60 (to be described hereinafter).

The lugs, flanges, or projections 42 at the ends 41 of the treads 40, in all but the longest or lowermost tread 40, should extend from the back or transverse face 44 of the recess 43 on the surface defining the end of the body 46 of the tread 40, for a distance substantially equal to twice the thickness of the risers 60. In the longest or lowest tread 40", the end 53 of the projection 42 may be only one riser 60 thickness distant from surface 44. The reason for this will become apparent as the assembly of this form 39 of the ladder is described.

IBRISERS The risers 60 of this first form 39 of the ladder of this invention may also be, and preferably is, a metallic casting and may be substantially planar in form and of rectangular configuration. The width of the riser 60 should preferably be slightly less than the width of the tread end recess 43 as defined by the distance between the inner longitudinal surfaces 49 and 50 of the projecting lugs 42 at the ends 41 of the threads 40. The length of the risers is variable from ladder to ladder but is a function of the distance between the treads 40 when the ladder is extended to its fullest length. In the ladders of this invention the risers for any given ladder are of equal length, and for any given ladder of the different forms or types illustrated, the risers are, with minor exceptions to appear later, identical.

Each riser 60 has an inner or tread oriented surface 61 and an opposite or outer surface 62 substantially parallel to each other and separated by the thickness of the riser 60. Each riser also has an upper end 63 and a lower end 64.

Projecting from the riser 60 at its lower end 64 (see FIG. 4) there may be a first or lower tread engaging flange 65 extending across the entire width of the riser 60 and having an upper 66 and a lower 67 surface. The lower tread flange 65 should lie substantially perpendicular to the riser 66 with the upper surface 66 of the flange 65 perpendicular to the risers inner surface 61. The flange 65 may extend somewhat more than two riser 60 thicknesses from the inner surface 61 of the riser, but this dimension is not critical to the function of the flange 65. Lying parallel to and spaced from the lower tread flange 65 by a distance slightly greater than the thickness of the tread 40 described above, there may be, and preferably should be, a second or upper tread engaging flange 68 extending perpendicularly from the inner surface 61 of the tread and extending across the width of the riser 60. The upper tread flange 68 has a lower surface 69 parallel to the upper surface 66, of the lower tread flange 65. The length of the upper flange 68 may be somewhat less than the length of the lower flange, but, again, this is not critical. Between the flanges 65 and 68 is a surface 70 parallel to the outer riser surface 62. It is preferred that the distance between the tread abutting surface 70 and the outer riser surface be slightly greater than the thickness of the riser 66 itself.

Extending between the tread abutting surface 70 and the outer riser surface 62, there are holes 71 corresponding to holes 45 in the ends of the treads 40. The holes 71 may have countersunk portions 72 adjacent the outer riser surface 62.

Between the inner 61 and outer 62 riser surfaces along the longitudinal centerline 73 is an elongated slot aperture 74 having longitudinal sides 75 and 76 and upper 77 and lower 78 semi-circular ends. A recessed surface 79 parallel to the outer riser surface 62 surrounds the aperture or slot 74. The distance between the inner riser surface 61 and the recess surface 79 may be approximately one-half /2) the riser thickness. At both ends 77 and 78 of the slot 74 the recess 79 may coincide with the slot 74, as shown in FIG. 7, although the other figures show the recess 79 extending below the slot 74 about the same distance as the recess 79 extends between the edges or sides 75 or 76 of the slot 74 and the longitudinal sides of the riser 60. In other words, the slot 74 may be /2 the width of the riser 6t and the recess 79 may be A the width of the riser 66. Both the recess 79 and the slot 74- may have a common longitudinal centerline 73.

Adjacent the semi-circular upper end 77 of the slot 74 along centerline 73 and projecting from the inner riser surface 61 may be a circularly cylindrical stub shaft or pin 80 of a diameter slightly less than the width of the longitudinal slot 74. At the end 81 of the pin 80 away from the riser 60, a pair of tabs or flanges 82 project from the pin 80 in opposite directions transverse to the longitudinal centerline 73 of the riser 60. The tabs may have circularly arched ends 83 the arcs being concentric with the axis of the pin 80. The distance between diarnetral extremes of the tabs or flanges 82 should be somewhat less than the width of the recess 79 surrounding the longitudinal aperture or slot 74, and the distance between the undersides 84 (see FIG. 5) of the tabs or ears 82 and the inner riser surface 61 should be slightly greater than the 7 thickness'of the riser 60 between the recess 79 and the outer riser surface 62.

On one pair of risers 85, the top pair when the ladder 39 is assembled, the flanged 82 shaft 80 is replaced by a hole 86, preferably countersunk, extending through the width'of the riser 85. The use of such a hole 36 will soon become readily apparent.

L-C-ASSEMBLING "ma LADDER Having described the ladder components, the assembly of these component parts 40, 60, and 85 may be illustrated conveniently.

One auxiliary member, a top spreader rung 90, in the form of a round bar is required to assure that the ladder 39 goes together properly and that it stays together. The spreader rung 90 should be the same length as the distance between the back or transverse recess faces 44 at opposite ends of the top or shortest tread 40. The spreader rung should have a drilled tapped hole 91 at each end 92.

The first step in assembling the ladder 39 is to build the first movable section consisting of the top spreader rung 90, the top risers 8S, and the top or shortest tread 40. It will be remembered that the top risers 85 are distinguished from the lower risers 60 in that the top risers 85 do not have the flanged 82 stub shafts 80 at their upper ends 63. The top tread 40 (the tread having the shortest distance between the recesses 43 at the tread ends 41) is connected to the top risers 85 by inserting each of the ends 41 of the tread 40 between the lower 65 and upper 68 tread engaging flanges of the pair of top risers 85, so that the back or transverse faces 44 of the recesses 43 make contact with the tread abutting surfaces 70 of the risers 85. The grooves 52 in the top 47 of the tread 40 should be oriented toward the upper ends 63 of the top risers 85. If this first step has been performed properly, the top risers 85 may be considered the vertical legs of a U-shaped sub-assembly with the tread 40 forming the lower or horizontal member of the ill-shaped sub-assembly. The tread end lugs 42 should extend beyond both sides and the outer surface 62 of the top risers 85 to act as guides for the lower risers 60 which will later be attached to the top risers 85.

Referring again to the U-shaped sub-assembly constructed during the first stage of assembly, it will be noted that the holes 45 in the ends 41 of the tread 40 are in alignment with the holes 71 in the lower ends 64 of the top risers 85. Screws or bolts 93 may be inserted in these holes to have their heads recessed in the countersunk portions 72 of holes 71 to securely attach the top risers 85 to the top tread 40 (see FIGS. 4 and 6).

The second step in assembling the ladder 39 is to install the spreader rung 90 between the upper ends 63 of the top risers by inserting bolts or screws 94 through the holes 86 of the top risers 85 into the threaded holes 91 in the ends 92 of the rung 90 (see FIGS. 1, 2 and 3).

Having completed the construction of the top sub-assembly comprising members 40, 85, and 90, the third step in assembling the ladder 39 is to interlock the next pair of risers, the first of the lower risers 60, into sliding connection with the top risers 85. If a lower riser unit 60 is placed at right angles (90) to a top riser 85 with the flanges 82 of the stub shaft 80 along and over the slot 74 in the outer surface of the top riser 85, it \m'll be seen that the shaft 80 may be inserted into the slot 74 since the flanges 82 of the shaft 80 are aligned with the slot aperture 74 (see FIG. 7). The third step in assembling the ladder '39 consists of so inserting the shaft 80 of a riser 60 into the slot 74 of the top riser 85 and then rotating the lowerriser 60 until it is parallel to the top riser 85 so that the lower ends of the risers 60 and 85 are adjacent each other. As the riser 60 is so rotated, the ears or flanges 82 on the shaft 80 will engage the recessed surface 79 adjacent the slot 74 to maintain the shaft 80 in the slot 74 (see FIG. As the lower riser 60 is brought into alignment with the top riser 85, it may be found that the projecting lugs 42 of the top tread 40 prevent perfect alignment of the two risers and 85. If such a problem is encountered the shaft 80 (of riser 60) may be slid in slot 74 to the top end 77 of the slot 74 so that the natural play between the two risers 60 and 85 (a result of the clearances involved due to the casting procedures) will allow the lower end 64 of riser 60 to slip past the projection lug 42 of tread 40. If the play is not enough to permit easy alignment of the risers 60 and 85, the natural resiliency of the riser 60 will permit the riser 60 to be sprung past the projecting lugs 42; actually, such a forced interlock" is preferred since it assures positive and safe connection between the movable subassemblies of the ladder 39 when it is in use.

A second lower riser 60 may be installed in the other top riser 85 by the same method as described above. The second tread 40, the shortest of the treads remaining, may then be installed between the tread engaging flanges 65 and 68 as was done in the first step in the assembly.

Subsequent lower risers 60 and treads 40" and 40' etc. may then be added to complete the installation of the ladder 39.

It will be seen that as the sections of the ladder 39 move relative to one another they are constrained to move along a straight line because of the cooperative guiding action of the slot 74-shaft combination and the projecting lug 42riser 60 combinations. Because the shafts 80 are interlocked in slots 74 by the tabs, ears, or flanges 82, and because the treads 40, 40', 40" and 40" are firmly attached to the risers and 60 by screws 93, there is no danger that the ladder 39 will become disconnected as it is used. It is also seen that the ladder may be readily disconnected for painting if such is desired.

This first form 39 of this invention may be hung on the side of a boat by means of straps or hooks engaged with the spreader rung at the top of the ladder.

II-SECOND EMBODIMENT OF THE LADDER IIATREADS The treads 101 of this form of the invention are planar in form and rectangular in configuration much like the treads 40, 40', of ladder 39. There may be grooves 102 (see FIG. 12) in the top surface 103 of the treads 101, 101', '101" and, to save Weight in the casting, there may be recesses 104 (see FIG. 13) in the bottom surface 105 of the treads 101, 101", etc. The top surface 103 of the treads 101, 101', 101" etc. may be slightly inclined'106 from back 107 to front 108 of the treads 10 1 so that a more nearly horizontal surface is presented to the user when the ladder 100 is set at angle to the surface to be scaled.

At each end 110 of the treads 101, there is a projecting lug 111 extending from the central portion of the tread 101 longitudinally of the tread 101. The length of the lug or tab 111 should be approximately as great as the thickness of the risers 130, to be described later. Running parallel to the end 110 of the tread 101 across the top 112 of the lug 111 should be a semi-circular groove 113 substantially as wide as the lug 111 is long.

To facilitate the interlocking connection between the treads 101, 101', 101", etc. and the risers 130, at each end 110 of a tread 101 there is provided, adjacent the projecting lugs 111 between the lug 111 and the back 107 and between the lug 111 and the front 108 of the tread 101, a series of steps or intermediate horizontal surfaces 114 and 1115 opening toward the bottom surface 105 of the tread 101 (see the perspective view of FIG. 12). The surfaces 114 and 115 define top and bottom tread interlocking seats respectively which will be referred to later. The surface 115 extends from front 168 to back 107 of the tread 101 and behind the projecting lug 111, producing a downward extension i116 of the lug 111.

The top tread 101, the second tread 1111, the third tread 101", etc. are all essentially identical, except, as in ladder 39, they are of increasing length; the increase in length being twice the thickness of the risers 130.

As mentioned above, stand-off means 120 are provided in this ladder; their use will become apparent later. The stand-off means takes the form of arms or bars 121 connected to the underside 105 of the top tread 101 (see FIG. 11). The bars 121 may be of substantially rectangular cross'section and may have adjustment holes 122 arranged in a line through their thickness. In the particular use shown in FIG. 11, there are three of these adjustment holes 122 in each of the pair of stand-off arms. For pivoting these stand-off arms 121 to the tread 101, a pair of pivot studs 123 may be disposed along the tread 101 and may extend from the bottom surface 105 of the tread 1M with a diameter such that the studs 123 will cooperate freely with the adjustment holes 122. The arms 121 may be maintained on the pivot studs 123 by a screw 124 (see FIG. 8), tapped into the stud 123, which maintains a disc or washer 125 against the arm 121 to hold it in place. Such an arrangement is entirely satisfactory since all the load on the stand-off arms 121 is borne by the cross-section of the pivot studs 123. One end of each arm 121 may have an offset portion 126 which, when the arms 121 are pivoted into working position (see FIG. 11), will bear on the surface from which it is desired to maintain the ladder 100. In use, rubber feet 127 may be slipped over the offset portions 126 so as not to mar the surface supporting the ladder 1110, especially if such a surface is the side of a small boat.

The common or lower risers 130 of this form 100 of the ladder are essentially flat rectangular castings having an inner or tread oriented surface 131, an outer surface 132, an upper end 133, and a lower end 134.

The lower end 134 of the riser 130 has a flange 135 (see FIG. 13) running across and beyond the width of the riser 131) and extending from the inner surface 13-1 of the riser 1311. Above and parallel to the upper surface 136 of the flange, there is an intermediate surface 137 extending from the inner riser surface 131 approximately half way to the end 138 of the flange 135. At the sides of the riser 131 the flange 135 extends backward beyond the outer or back surface 132 of the riser 131 to form guide tabs 139. The flange upper surface 136 and the intermediate surface 137 cooperate with the step surfaces 114 and 115 respectively of the treads 101, 131, 101" etc. when the ladder is assembled (see FIG. 13).

Located in the riser adjacent the flange 135 is a rectangular lug receiving hole or aperture 141) which has a width equal to the width of the tread lug 11-1 and a height approximately equal to the lug 111 thickess plus the riser 130 thickness. The aperture is so located that the bottom aperture side 141 is below the upper flange surface 136 resulting in the aperture 141 being partially closed by the flange 135. The distance between the bottom aperture side 141 and the upper flange surface 136 is equal to the distance between the bottom tread surface 105 and step surface 115 of the tread 101. In the top side 1412 of aperture 140 is a notch 143 opening into the outer riser surface 132. The upper or top aperture side 142 is flat, the significance of this will become apparent later.

In the central portion of the riser 130 there is a rectangular slot-like aperture 145 extending along the centerline of the riser. The slot aperture has a full rectangular opening on the inner surface 131 of the riser 130, but at the outer surface 132 of the riser a lipor flange 146 may extend into the opening 145 on the bot tom 147 of the slot, and along both sides 148 of the slot 145 except for about an inch at the top 149 of the slot 145, This flange 146 provides a recessed surface surrounding the aperture 145 sirnilar to the recess 79 described as a part of the first form 39 of this invention.

Extending from the inner riser surface 131 immediately above slot aperture 145 (see FIG. .13) and flush with the top edge 149 of the slot 145 is a rectangular stub shaft or pedestal 150 with its bottom side 151 an extension of the top side 149 of the aperture 145. The stub-shaft 150 is as wide as the clear opening between the flanges 146 in aperture 145. The shaft 150 has a flange 152 extending from its end around the two sides and the bottom 151 of the shaft 151). The extreme width across flanges 152 should be slightly less than the width of the slot 145 at the inner riser surface 131. The overall height of the shaft 151? and the flanges 152 should be equal to the thickness of the riser 1311, while the distance between the inner riser surface 131 and the flanges 152 should be only slightly greater than the thickness of slot flanges 146. The overall longitudinal extreme dimension of the shaft 15a and flange 152 should be less than the distance from the end of flange 146 in slot 145 to the top 149 of the slot 145, i.e. the keyhole opening in the top of the slot must allow the free passage of the enlarged end of the stub shaft 151) of an adjacent riser 131 The overall proportions and the detailed dimensions of the riser 130 as thus far described should be such that, when two identical risers 1313 are placed in juxtaposition with the outer surface 132 of one (A) next to the inner surface 131 of the other (B), the following conditions should be true:

(1) The extreme bottom surface of said one (A) rides on the intermediate flange surface 137 of the other (B); and

(2) The guide tabs 139 of said one (A) straddle or span the width of said other riser (B); and

(3) The stub-shaft 151 of said other (B) with its flange 152 projects through the keyhole end of the slot aperture 145 of said one (A) with the flanges 152 of said other (B) clearing the slot flanges 146 of said one (A).

The risers 131 should be so configured that if Condition 1 above is not fulfilled (as by something being between the bottom extremity of said one (A) and surface 137 of said other (B)), then Condition 3 cannot occur or be fulfilled. This is the safety interlock feature of this form 1110 of the ladder, and will become more clearly understood later.

At the upper corners of the riser 130 there is a second pair of guide tabs 153 which extend beyond the inner riser surface 131 much the same way as guide tabs 139 extend beyond the outer riser surface 132 at the lower corner of the riser 1311.

The upper or top risers are identical to the lower or common risers 131} with a few minor exceptions. First, the upper or second guide tabs 153 are not present on the top risers 160. Second, a pivot stud 161, similar to the pivot stud 123 on the underside 105 of the top riser 101, is located on one side of the inner top riser surface 131 between the slot aperture 145 and the edge of the top riser 160 adjacent the top 149 of aperture 145. On this stud 161 may be mounted an angled hanger arm 162 having a broadened bearing surface 163 at its free end. The pivoted end of the hanger arm 162 has a hole 164 therein for cooperation with stud 16 1. The arm 162 may be maintained on st-ud 161 by a screw 165 and washer 166 combination as described before for studs 123.

Located on the upper inner rear corner of a top riser 160 may be a hanger backstop 167 consisting of a hood cast integral with the riser 160 and which limits the motion of the hanger arm 162.

11 II-C-ASSEMBLING 'IHE LADDER In assembling this form 100 of the ladder of this invention, two auxiliary pieces, namely, a retainer pin 170 and a retainer spring 174, are required. FIGURE 16 discloses, in perspective, the retainer pin 170 as a cylindrical element having one rounded end 171 and an opposite flat end 172 having a smaller diameter extension 173 concentric with the pin 170. The major diameter of the pin 170 is approximately equal to the thickness of the upper 160 or lower 130 risers. In conjunction with the retainer pin or pins 170, the spring 174 i used. Spring 174 may have a coefficient of lbs/in. (not critical) and should have an outer diameter no greater than the major diameter of pin 170 and an inner diameter greater than the minor, or extension 173, diameter.

In this form 100 of the ladder, as in all the forms of this invention, the basic movable unit of the ladder is a U-shaped sub-assembly comprised of a tread and two riser which cooperate with adjacent sub-assemblies. In the case of this form 100 of the ladder, the U-shaped subassembly is made up by inserting the projecting lug 111 of the top or shortest tread 161 into the lug aperture 14% of one of the top risers 160 making sure that the lug groove 113 is toward the riser slot-aperture 145. It will be found that step surface 115 will mate with the riser bottom flange 135 top surface 136, the step surface 114 of the tread 10 1 will mate with the flange 135 intermediate surface 137, and the tread lug 111 bottom extension 116 will mate with the riser lug aperture 140 bottom side or surface 141 as the lug 111 is moved into aperture 140 and then moved downward toward flange 135. The angles and the configuration of the lug 111, the flange 135, and the lug aperture 140 provide a great degree of interlocking rigidity between the tread 101 and the top riser 164), but if the tread lug 111 is permitted to move upward in lug aperture 140 this interlocking rigidity is lost and the members become uncoupled.

To maintain the lug 111 in the lower portion of the lug aperture 140, the retainer pins 170 are inserted between the groove 113 in the top of the lug 111 and the top or upper face 142 of the lug aperture. By means of notch 143 in the lug aperture 140, one retainer pin 176 is inserted in each end of the groove 113; the retainer pin extensions 173 should be oriented toward each other. One end of the retainer spring 174 may then be inserted, by means of notch 143, over one of the retainer pin extensions 173. However, because of the length of the spring 174, the other end of the spring 174 will not readily slip over the other pin extension 173. To seat the spring on the unengaged pin extension 173, the blade of a small screwdriver may be inserted between the coils of the spring 174 and the spring 174, by virtue of the low spring coeflicient involved, may be compressed to fit over the remaining retainer spring extension 173. The joint between the top tread 101 and one of the top risers 160 is thus seen to be a positively interlocked joint which cannot, so long as the retainer spring 174 and retainer pins 170 are in place, become disengaged when the ladder is in use.

To complete the top U-shaped sub-assembly the other top riser 160 may be connected to the top tread 101 in the manner described above.

The second U-shaped sub-assembly may not be connected as a unit to the top sub-assembly, but must be built upon the top sub-assembly. First the risers 130 of the second sub-assembly must be interlocked with the top risers 160. This may be accomplished by aligning the inner surface 131 of riser 130 against the outer surface 132 of top riser 160' so that flange 152 stub shaft 150 of riser 130 may engage the keyhole end of the slot aperture flanges 146 of top riser 160. In order that this engagement may occur, the bottom of top riser 160 must be against the bottom flange 135 intermediate surface 137 of riser 130, riser 131) must be within the guide 12 tabs 139 of top riser 160, and the guide tabs 153 at the upper end of riser must span top riser 160. (See the three conditions listed under head II-B above.)

After a lower riser 130 has been thus interlocked with each of the top risers and been drawn to its furthest extended position, the second U-shaped sub-assembly may be completed by installing the second tread 101' between the engaged risers 1311 in the manner described above. When the second sub-assembly is completed and slid back up against the top sub-assembly by means of the slidable interlocking connection between the stub shafts 150 in slot-apertures 145, it will be found that the stub shafts 150 will not disengage the slot flanges 146 as would be expected according to the reverse of the construction or riser interlocking procedure. This is because the portions of tread 101' (of the second subassembiy) between the top surface 103 and the step surfaces 114 of tread 101 are now between the riser 130 bottom flanges intermediate surfaces 137 and the bottom edges of the top risers 160. Thus Condition 1 of section II-B above is not satisfied,.the risers cannot become disengaged from each other, and the safety interlock feature is in effect. It is thus impossible for the ladder to come apart in use, no matter how easily and rapidly it may snap together.

The rest of the ladder may be assembled as set forth above.

In use, the hanger arms 162 may be hung over a window sill or the gunwale of a small boat and the stand-ofi means 120 attached to the top riser 101 may be pivoted from dotted line position 120' shown in FIG. 11 into place and braced against a wall or the side of a small boat to provide an angle to the installed ladder so that it may be easily climbed or descended by a person using the ladder.

III-THIRD EMBODIMENT OF THE LADDER The third form of the ladder of this invention resembles the first and second ladder forms 39 and 100, in that the assembled ladder comprises U-shaped subassemblies movable relative to each other, but in the case of the third form 180 now under discussion, the feature of castability of the component parts is more readily discernible and contributes more to the scope of the invention. The third and fourth ladder forms 180 and 400 of this invention are closely related yet are, in some important features, quite independent. In describing the third embodiment 180 of the principles of this invention reference will be had to FIGURES 1735 with FIG- URES 17-2-1, 33, and 34 particularly noted.

IIIAGENERAL COMPONENT Having reference to FIGS. 17 and 18, the ladder 180 is comprised generally of treads 181 and risers 200, as is true of ladder forms 39 and 100 described before, combined into the U-shaped sub-assemblies basic to this invention. These parts 181 and 200 are of cast metal, preferably aluminum, and generally require no machining, thus assuring a low cost product.

Ill-A-I -T reads The treads 181, 181', 181" etc. utilized in this form 180 are essentially planar of rectangular proportions having parallel upper 182 and lower 183 surfaces, ends 184, front 185 and back 186 edges, and may have an inclined portion 187 in the upper surface 182. There may be be recesses 188 in the lower surface 183 with strengthening ribs 189 between these recesses. Slot-like apertures 190 may be present in the treads 181, 1 81, etc. to reduce the weight of the ladder 180 and to provide increased traction for the user of the ladder 180.

At the ends 184 of the treads 181, the lower surface 183 is stepped toward the upper surface 182 resulting in a vertical, or riser flange end engaging face 191 and a horizontal step surface 192, both surfaces 191 and 192 extending between the front 185 and back 186 edges of the treads 181 (see FIG. 34). Centrally disposed of each end 184 of treads 181 there is an upwardly and outwardly extending lug 193 (see also FIGS. 33 and 34) having its bottom surface 194 intermediate of the tread top surface 182 and the step surface 192 and also have an inner or tread oriented face 195 and an opposite outer face 196.

Each of the treads 18 1, 181', 181" etc. is of a different length, the difference in length in each case being constant and equal to twice the thickness of a riser 200.

The risers 200 used in form 180 of this invention are basically hybrid improvements over the risers 60 and 130 described in sections 1 B and II-B above. Again, each riser 200 is essentially planar in form and rectangular in configuration. Each riser 200 has an inner or tread oriented face 201, an outer face 202, a bottom end 203, a semi-circular upper end 204, and longitudinal edges 205, and each may be completely cast in a single piece. To avoid confusion in this discussion, the character 200 represents all risers except the top or inner pair. Fig. 24 shows a riser similar to riser 200.

At the bottom 203 of each riser 200 there is a guide tab 206 which extends from each side or edge 205 of the riser 200 and also extends beyond the outer surface 202 of the riser 200 a distance of one riser thickness forming a guide surface 207 in line with its riser edge 205. Instead of having both faces of the tab 206 parallel to riser edges 205, the outer face 208 (see FIG. 33) of tab 206 may be bevelled to intersect with surface 207 at the end of the tab 206. The upper extremity of the tab 206 is above the bottom 203 of the riser 200 a distance equal to the thickness of a tread 181.

A flange or lip 209 extends perpendicularly from the riser inner surface 201 at the bottom of the riser 200 and has a tread seating surface 210 as its upper surface. The distance between the riser bottom 203 and the tread seating surface 210 is equal to the distance between the tread bottom surface 183 and the tread step surface 192 (see also FIG. 34).

Intermediate of the edges 205 of the riser 200 and extending upward from the bottom 203 of each riser is a notch 211 as wide and as deep as the tread lug 193 is wide and long. The upper portion of notch 211 is hooded by a boss 212 (see also FIGS. 24, 25, 33, and 34) on the inner surface 201 of the riser 200, with the lower edge 213 of the boss 212 one tread 18 1 thickness from the bottom edge 203 of the riser 200. The inner surface 214 of the hood boss 212 is in the same'plane as the riser inner surface 201, but such relationship need not be adhered to to accomplish the purpose of this structure (refer to FIG. 34). In the sides of the notch 211 there may be recesses 215 opening onto the outer surface 202 of the riser 200 to provide room for boss 212 of the adjacent lower riser when the ladder is collapsed.

Along the longitudinal centerline of the riser 200 above the boss 212 and below the top end 204 of the riser 200 is a slot-like aperture 216 (similar to apertures 74 and/or 145) having a semi-circular lower end 217 and sides 218 around which is a recessed surface 219 open to the riser inner surface 201. The recessed surface 219 extends almost to the riser edges 205 and almost to the boss 212. In the inner surface 201 about half /z) way between the ends 203 and 204 of the riser 200 and adjacent each riser edge 205 is an edge notch 220 between the riser edges 205 and the recess 219 but not as deep as the recess 219. The thickness between the recess surface 219 and the riser outer surface 202 may be one half /2) the total riser 200 thickness.

Extending from the riser inner surface 201 above and adjacent to slot aperture 216 is a circular stub shaft 221 (a little longer than the thicknesses of the riser) having a hat portion 222 on its upper part (FIG. 17 and 24).

Around the lower half of the periphery of the shaft 221 at its end is a semi-circular flange 223 having a flat portion 224 opposite and parallel to the shaft flat portion 222 and separated from the shaft flat portion 222 by a distance slightly greater than the width of slot aperture 216. The distance between the riser inner surface 201 and the flange 223 should be slightly greater than the distance between recessed surfaces 219 and the riser outer surface 202. The diameter of stub shaft 221 should preferably be slightly less than the slot 216 width.

Concentric to the shaft 221 axis in the riser outer surface 202 there may be a recess 2 25 of less diameter than of shaft 221.

Other openings may be observed in FIG. 17 than are described herein, but these openings are dictated by casting practice and serve no function or purpose embodied in this invention.

It is again stressed that all the risers 200, and also the top risers 230 if some machining is permitted, may be cast from the same mold.

1II-BTOP U-SHAPED SUB-ASSEMBLY The uppermost of the basic U-shaped sub-assemblies featured in this embodiment of the invention includes modified top risers 230, top riser extensions 240, standoff arms 270, and a spreader rung 290, some of which have not been described before.

As in the previous forms 39 and of this invention described, the top risers 230 of ladder are essentially identical to the lower or common risers 200. The lower end 231 of the top riser is identical to the lower end 203 of the lower risers 200 except that the upper extremity of guide tabs 206 are only about one half /2) tread thickness above the lower edge 231 of the top riser 230 rather than about one full tread thickness as in the lower riser 200.

At the upper end 232 of the top riser 230, a hole 233 (see FIG. 19A) may be drilled through the riser 230 concentric with the stub shaft 221 opening into recess 225. A recess 233' also may be drilled surrounding the hole 233 at the inner surface 201 of the top riser 230 (see also FIG. 26).

It is now necessary to define a front 234 and a back 235 riser edge in lieu of the general edges 205 defined previously. It should also be remembered that, viewed from the riser outer surfaces 202, one top riser 230 is a mirror image of the other. Along the front edge 234 of the top riser 230 opening into the riser outer surface 202 is a guiding recess 236 at least as long as the slotaperture 216 commencing at the upper end of guide tab 206. Just adjacent tab 206 at the lower end 237 of recess 236, a notch 238 extends entirely through the riser 230 to the inner surface 201.

In all other respects the top risers 230 are identical to the lower or common risers 200.

IIIB2T0p Riser Extension-Style A In conjunction with form 180 of this ladder, there is an additional pair of vertical members 240 or 260, herein called top riser extensions, because they cannot properly be called risers as there is no tread attached to them. They are rather primarily used to increase the effective length of the ladder. Two forms of the top riser extensions are shown in FIGS. 17, 19 and 20 and they differ only in auxiliary functional details. Again, all the various parts of the member 240 are cast integral with the member.

The top riser extension Type A in FIGS. 17-19A is basically a rectangular planar element having a lower end 241, an upper end 242, an inner or tread oriented face 243, an outer face 244, and is preferably as long as the risers 200 or 230 used in conjunction therewith. The riser extension 240 also has front 245 and back 246 edges longitudinal of the member. Along the junctions of the outer surface 244 and the front and back edges 245 and 246 there are flanges 247 and 248 respectively extending perpendicular to the outer surface 244 and having inner faces 249 and 250 respectively facing each other and separated from each other by a distance equal to the width of a top riser 230. From the inner surface 249 of front flange 247 at the bottom 241 of the extension 248 there is a tab 251 extending over and parallel to the outer surface 244.

In the outer surface 244 at the bottom 241, or lower end, there is a boss 212 nesting recess 252. In the lower portion of the extension there may be a lightening hole 253.

A longitudinally oriented slot 254 is present in the upper central portion of the extension 248 in which the stub shaft 221 of the top riser 230 may cooperate. Between the slot 254 and the lightening hole 253 on the inner surface 243 there is a circularly arced raised standoff arm 270 seating or guiding rib 255 extending from the back edge 246 obliquely upward and at least partly across the riser extension 240. A recessed surface 256, similar to recessed surface 219, surrounds the slot 254 on its sides and lower end on the inner surface 243 of the extension 240.

A hand-hold 257 may be formed along the upper portion of the front edge 245 of the extension 240 and may be closed by a grasping strip or bar 258.

On the inner surface 243 along the upper back riser edge 246 there may be a raised rib 259 (see FIG. 19) for guiding the stand-off arms 270 as the ladder is telescoped into its closed position.

As is the case with the top risers 230, each member of the pair of top riser extensions 240 is a mirror image of its mate.

III-B3T0p Riser Extension-Style B The alternate top riser extension 208 of Type (B) shown in FIG. 20 is essentially identical to extension 240 of Type (A) in all functional structure details and dilfers only in appearance. Instead of the one large hand-hold 257 as on extension 240, extension 260 incorporates two separate hand-holds 261 and 262; one, 261 along the front edge 245 of the extension 260 intermediate of its ends 241 and 242, and the other 262 along the upper end 242 of the extension 260.

In addition to the tab 251 described on riser 240, an additional tab 263 may be found on extension 260 (Type B) opposite tab 251 on the inner face 250 of'rear flange 248. The apertures shown in FIG. 20 are dictated by casting practice and are not material to this invention and figure shows the right alternate top riser extension 260; the left member of the pair required is a mirror image of that shown in FIG. 20.

IIIB4AuxiliaIy Components Before describing the assembly procedure of the upper movable section of the ladder 180 discussed under heading III, it is considered advantageous to describe two auxiliary units of this section; namely, the stand-off arm assemblies 270 and the spreader rung 290.

IIIB4-uSTAND-OFF MECHANISM 270 In ladder form 16!) (FIGS. 8 and 9) the stand-01f arms 121 were adjustable only by means of apertures 122. In this form 180 of the ladder the stand-elf means 270 are continuously adjustable. While not shown in detail, each of the two stand-oif means 270 comprises a circularly arched arm 271, a bolting strip 272 (see FIG. 19A), two substantially square bolt blocks 273, and two bolts or screws 274.

The arched arm 271 is curved throughout its length and may be of any degrees of arc, but prefer-ably it contains approximately 95 of arc. The arm has a flat inner or riser extension engaging surface 275 and an outer bolting strip engaging surface 276 parallel toeach other. The inner surface 275 has a recess 277 along its arcuate 16 centerline. An aperture 278 running substantially from end to end of the arm 27 1, opens from inside the recess 277 to the outer surface 276. From one end of the arm 271 extends a shaft-like projection 279 upon which may be mounted a rubber foot 280, similar to the type used on the ends of crutches or canes.

The bolting strip 272 is arched to the curvature of the arm 271, is considerably shorter than the arm 271, and is of less width than the arm 271 on which it rides. It has a flat arm engaging face 281. Drilled through the bolting strip 272 into the flat face 281 are three holes; a large rung end engaging hole 282 and, spaced along the length of the strip 272 on either side of hole 282, two smaller diameter holes 283 for bolts or screws 274.

The bolt blocks 273 are identical, being of essentially square shape having sides shorter than the width of recess 277 and having tapped bolt 274 receiving holes 284 centrally disposed therein.

The stand-off mechansim 270 is assembled by: placing the flat arm engaging surface 281 of the bolting strip 272 against the outer or strip engaging face 276 of the arm; inserting the bolt blocks 273 into the recess 277 on the opposite side of the arm; and threading the bolts 274 through the bolt holes 283 in the strip 272, through the arm aperture 278, and into the tapped holes 284 in the bolting block 273. It is essential that neither the bolt blocks 273 or the bolts 274 extend beyond the riser extension engaging surface 275 but are contained wholly in recess 277. Also, the rung aperture 282 should be entirely clear of obstructions (see FIG. l9-A).

The other of the two stand-off mechanisms 270 should be a mirror image of the first.

IIIB-4.-IISPREA DER RUNG 290 The spreader rung 290 may be fabricated from a length of metal rod of any satisfactory cross-section. It has at each of its ends 291 (see FIGS. 18 and 19A) a portion 292 of reduced diameter only slightly less than the diameter of the rung hole 282 in the stand-01f bolting strip 272. This is the stand-off 270 pivot means and should have a length somewhat greater than the combined thicknesses of the stand-01f arm 271 and the bolting strip 272. The reduced diameter of the stand-off pivot length 292 results in a shoulder 293 at the inner end of length 292. (See FIG. 29 which also applies to form 400 of the ladder.) a

Tapped into each end 291 of the rung 290 is a hole 294.

lIIB5Assembly of the Top Sub-Assembly The first step in the assembly procedure is to the left top riser 230 with the left top riser extension 240 and the right top riser 230 with the right top riser extension 240; in both cases the procedure is identical. First the top riser 230 should be placed against the top riser extension 240 at right angles to the extension 240 with the inner surface 201 of the riser 230 against the outer surface 244 of the extension 240. (Refer to FIG. 25 which shows the components of the fourth form 400 of this invention; but the method of assembling the top sub-assemblies of both the third and fourth forms and 400 are identical.) It will be found that becauseof the flat portions 222 and 224, on the shaft 221 and flange 223 of the riser 230, respectively, the stub shaft 221 may be engaged as shown in FIG. 25 with the slot aperture 254 of the extension 240. The riser 230 is then rotated about stub shaft 221 until its lower end 203 is adjacent the extensions lower. end 241 and the edges 234 and 235 of the riser 230 are between flanges 247 and 248 of the extension 240. As the riser 230 is rotated the flange 223 of riser 230 will engage the recessed surface 256 surrounding slot aperture 254, but that-the riser 230 is prevented from lying flat against the extension 240 because of the tab 251 at the bottom of the front extension flange 247. If the stub shaft 221 is moved to the upper extremity of slot aperture 254, it willbe found that the tab 251 will pass through the notch 238 at the lower end 237 of the guide recess 236 permitting the riser 230 to lie flush against the extension 240. (Because the end 184 of the top tread 181 prevents the extension 240 from attaining such a position (relative to the riser 23%) when the tread 1'81 is later attached, the top risers 239 and the top riser extensions 240 cannot become disengaged when the ladder is assembled and in use).

Assuming that both top risers 230-extension 240 combinations have been engaged, the top tread 181 is engaged with the top riser 230 for the second step in the assembly by inserting the tread lug 193 into the notch 211 at the bottom 203 of the riser 230 (see FIG. 34). The surfaces 191 and 192 of the end 184 of the tread 181 will nest against the riser flange 209 end, the tread seating surface 210, and riser inner surface 201, respectively, of the riser 230. The lug 193 will extend into the recess formed by the housing boss 212 with the inner face 195 of the lug 193 against inner boss surface 214; the lower edge 213 of the boss 2 12 will be against the upper surface 182 of the tread 181. The angle between the upper surface 182 of the tread 181 and the inner surface 201 of the riser 230 is limited to a maximum of 90 because of the interlocking nature of the surfaces at the ends of the tread 181 and the riser 230 (or riser 200 as occurs later).

Now, assuming the other top riser 230 has been engaged with top tread 181, the third step, providing a stable base for subsequent stages of assembly, is to install the stand-off mechansims 270 and the spreader rung 290 between the top riser extensions 240 and the upper ends 232 of the top risers 230. The left stand-off arm 271, with its attendant parts attached thereto, is placed against the inner surface 243. The arm riser extension engaging surface 275 should lie flat against surface 243 with the arc of the arm 27d opening toward the upper end 242 of the riser extension 240 and backing along or against the guide rib 255, and the rubber footed 280 .end of the arm 271 should project beyond the rear edge 246 of the extension 240. The spreader rung 290 is then engaged with the stand-off mechanism 270, the extension 240 and the riser 230 by inserting the reduced diameter stand-01f pivot portion 292 of the rung 290 through the rung aperture 282 in the stand-off bolting strip 272 and into the recess 233' at the end of the riser stub shaft 221 engaged in the slot 254 of the top riser extension. A bolt or screw 295 is then inserted into the tapped hole 294 in the end 291 of the rung 290 through hole 233 in the stub shaft. When the bolt 295 is tightened the shoulder 294 of the rung should be against the stand-off bolting strip 272 and the end 291 of the rung 290 should be in the recess 233' of the stub shaft 221 (see FIGS. 19-A and 29).

When the other stand-off mechanism 270 has been installed, the top sub-assembly is completed.

III-CAssEMBLY OF THE LADDER Having fabricated the top riser sub-assembly, it may be used as a stable base for the addition of the adjacent lower riser 200 sub-assemblies. To complete the ladder 180, a pair of lower risers 200 and the second tread 181', the shortest of the treads remaining, are engaged into a U-shaped unit with the risers 200 at right angles to the tread 181. The U-shaped unit thus formed is engaged with the top risers 230 by interlocking the lower riser 200 stub shafts 221 with the top riser 230 slot apertures 216 and swinging the top 230 and lower 200 risers into line. It will be found that the top riser 230 guide tabs 205 project into the path of the lower risers 200 and prevent ready alignment. The natural resiliency of the lower risers 200 is such that when the lower riser edge 205 notches 22% intermediate of the ends 203 and 204 of the risers 200 are oriented in juxtaposition with the guide tab 206 bevelled surfaces 208 and force is applied to the tread 181, the risers 200 will spring apart, move past the guide tabs 206, and come into interlocked alignment with the top risers 230. Because of the fact that the risers 200 may not achieve an angle greater than with respect to the tread 181 and because the resiliency of the risers 200 is such that the risers 200 will not disengage the guide tabs 206 unless in the proper position with force specifically applied to the risers 200 to spring them apart, the second tread sub-assembly cannot become disengaged from the top riser sub-assembly when the ladder is in use.

By the distance between the stub shafts 221 and the guide tabs 206, the various sub-units of the assembled ladder are maintained in rigid alignment with each other in any of the positions of the ladder between and includ ing the fully extended and fully retracted positions.

The ladder :may be completed by installing the remain ing risers 200 and treads 181" etc. on the base thus far assembled.

III-DHANGER HOOKS AND RECEPTACLES Referring to FIGS. 17, 19, 20 and 21, it may be seen that a projection has been incorporated at the upper end 242 of the top riser extension 240 or 260 extending from the rear edges 246 thereof. This is the hanger hook means 300. It is comprised of a planar body portion 301 having laterally extending lugs 302 at its end 303 extending perpendicularly from the body 301 on either side thereof. The end 303 of the hook body 301 has a substantially vertical edge 304 intersecting the upper edge 305 of the body 301 at the pronounced hump or corner 306 (see FIGS. 20 and 21). The lower edge 307 of the body 301 extends upwardly for a short distance from the lugs 302 parallel to the vertical edge 304 to a rounded weight hearing corner 308 and then extends to the back edge 246 of the extension 240 or 260.

The hook means 300 is specifically designed to cooperate in a special hanger receptacle 310 which may be of cast construction (refer to FIG. 21). The receptacle is essentially a boss or housing partially enclosing a cavity 311. FIG. 21 shows the hook 300 inserted into the cavity 311 through a slot 312 in the front 313 of the receptacle 310. The slot 312 has right angled extensions 314 (see PEG. 18) near its upper end to permit insertion of the lugs 302 at the end 303 of the hook body 301 into the cavity 311 Adjacent the lower end of the slot 312 the receptacle 310 has a cylindrical raised weight bearing hump or boss 315 so that, when the hook body 301 is inserted into the receptacle 310, the lugs' 302 naturally mate with the recess 316 below the hump 315 with the hump 315 mating against the corner 308 in the lower edge 307 of the hook body 301. At the upper portion of the receptacle 310 (as shown in FIG. 21) the slot 312 ends at an inclined plane surface 317. The location of this surface 317 is important when the receptacle 310 is used on a vertical surface, as will be seen later.

The receptacles 310 for each hanger hook means 300 may be incorporated in a mounting strip 318 as shown in FIG. 18, or they may be separate casings applied indi vidually to a surface as shown in FIG. 23.

In describing this invention the ladders embodied therein are illustrated as being attached to the side of a small boat 320 (FIGS. l7, l8 and 19), It is a well known fact that the overall density of the human body is less than that of water, which accounts for the buoyancy of the human body in water. If a small boat boarding ladder were merely hung over the gunwale of the boat and the ladder were in use in choppy or rough water so that the boat is rolling and/ or pitching severely, there is a great possibility that if someone were climbing the ladder and was suddenly immersed in the Water by the rolling action of the boat, that, since the person is grasping the ladder, the ladder may become unhooked from the gunwale because of the interaction of the persons normal buoyancy and the rolling of the boat. If such happens the person using the ladder may be injured severely by falling against the side of the ship and the ladder may be lost in the water. Also, it is entirely possible that, by the dynamic acceleration forces alone which are present, the ladder may become unhooked from the gunwale without anyone being on the ladder unless there is some means present to keep the ladder securely anchored to the boat. In this invention, the cooperating configurations of the hook means 300 and of the receptacles 310 assure that the ladder will not become disengaged from its support at any time the ladder is extended.

Having reference to FIG 17 which shows the ladder 180 hung on the transom 321 of a small boat 320, the ladder 180 is installed by engaging the hook means 300 with the receptacles 310 so that the lugs 302 nest in recess 316 while the ladder 180 is in its short telescoped condition. Once the hooks 300 are engaged with the receptacles 310, the retracted tread 181 groups may be eased downward. As the rung 290 moves downward carrying the stand-off mechanisms 270 with it, the stand-off arms 271 will begin to engage the stand-off seating ribs 255 on 'the inner surface 243 of the riser extensions 240 (269) and the arms 271 will move along the ribs 255 so that the rubber tipped feet 280 move away from the extensions 240 (or 260) until the rung 290 is at its maximum downward position in slot 254 of the extension 240. At this time, if the stand-01f mechanisms 270 have been properly adjusted to the particular installation encountered, the feet 280 will be hearing on the transom 321 of the boat 320 below the hanger receptacles 310. At this time, the corners 306 of the hanger hook bodies 301 may be either wedged against the inclined plane surface 317 of the receptacles 310 or lying in close proximity to the plane surface 317, and the hook lugs 302 will be securely and snugly engaged in recesses 316 of the receptacles 310 (as shown by the solid lines in FIG. 21). Thus the hooks 300 cannot be disengaged from the receptacles 310 until and unless the corner 306 is permitted to move away from the inclined surfaces 317 to permit the lugs 302 to move upward and out of recesses 316 (as shown in the dashed lines in FIG. 21), but to provide such a hook disengaging position the riser extensions 240 (or 260) must move to be parallel with the transom 321. Because the stand-off mechanisms 270 are adjusted with the feet 280 against the transom 321 the riser extensions 240 cannot move parallel to the transom 321 so that the hooks 30G cannot become disengaged from receptacles 310. The ladder 180 may be unhooked from the boat 320 only if the stand-off mechanisms 270 are retracted which means that the rung 299 must be raised relative to the extensions 240 so that the stand-off arms 271 disengage the stand-oft seating ribs 255. It is thus impossible for a properly adjusted fully extended ladder 180 to ever come loose from the supporting surface.

It is not necessary that the ladder 180 be mounted on a nearly vertical surface as a b-oats transom 321. Because the slot 312 of the receptacle 310 extends between the bosses 315 the hanger hook 369 may be in a position 90 to the position shown'in solid lines in FIG. 21 and still have the lugs 302 engaging the recesses'316. Thus the ladder hanging receptacles 310 may be mounted on the top edge of a boats gunwale 322 with the stand-offs 270 resting against the side shell 323 of the boat 320 (see FIG. 19).

IV-FOURTH EMBODIMENT OF THE LADDER The fourth form 400 of the ladder of this invention is particularly directed toward a ladder utilizing the fewest number of cast parts for a ladder of any length desired while still featuring the interlocking sliding action of the forms 39, 100 and 180 described previously. In this form 400 of the invention, the top riser extensions 450 are identical rather than being left-handed and righthanded and the treads 410 are comprised of two interlocking castings adjustable to any length rather than the risers each being of different fixed lengths.

2t) IV-AGENERAL COMPONENTS IV-A 1-Treads The treads 410 of this form 460 of the ladder of this invention are comprised in all cases, of two identical interlocked castings 411 (see FIGS. 30-35) of such a nature that any tread member 411 may be coupled with any other, and the pair thus formed may be used in any tread 410 position. It will be recalled that previously described embodiments and forms 39, 100, and 180 of this invention require separate castings for each tread since all the treads of a given ladder are of different length. If the ladder is of more than two treads in length, the tooling costs of the previous forms of the ladder become higher than the same costs of the fourth form 400 of the ladder of this invention.

Referring to FiGS. 30-35, various views of the tread members 411, unmated and mated, and the assembled tread 410 are shown. FIG. 30 shows a plan view of a tread member 411 in solid lines with the tines 418, 419, and 420 of a cooperating tread member 411 shown in dashed lines. The individual tread members 411 are planar in general form and rectangular in configuration having, for purposes of description, a front edge 412, a back edge 413, an upper surface 414, a lower surface 415, an open end 416 and a closed end 417. More specifically, each tread half 411 is comprised of a plurality of tines, a front tine 418, a rear tine 419, and at least one middle tine 420, all extending from the closed end 417 to the open end 416 of the tread member 411.

The closed end 417 of each tread member 411 includes a lug 193 and step surfaces 191 and 192 as described in conjunction with the treads 181 of the third embodiment 186 of the ladder.

Referring to FIGS. 30, 31, and 32 specifically, the front tine 418 is wider along its upper edge than the other tines and has a longitudinal cutaway portion 421 along the front face 412 of the front tine 418 which opens into the lower surface 415 of the tread half 411. Along the upper surface 422 of the cutaway portion 421 there may be a series of notches 423 and 424 adjacent the closed end 417 of the tread member 411; a group of notches 423 immediately adjacent the closed end 417 spaced regularly from each other; and adjacent the series 423, a long notch 424. Along the rear face 425 of the front tine or finger 418 adjacent the open end 416 of the tread member 411 is a notch 426 opening into the upper member surface 414.

The middle tines 420 may be plain and un-notched and run parallel to the front tine 418 to the open end 416. The middle tines 421} and the front tine 418 lie in the same plane in their upper edges 427, while the lower edges 428 of the front tine 418 and middle tines 420 do not extend to the lower surface 415 of the member 411. The middle tines 420 may have flanges 429 at their lower edges 428 parallel to the lower surface 415.

The rear tine 419 is parallel to the middle tines 420 but lies below the middle tines with its lower edge 430 in the lower surface 415 of the member 411 with its upper edge 431 as far below the member upper surface 414 as the front tine 418 front recess (cut-away portion) 421 upper surface 422 is below the member upper surface 414. On the upper end (adjacent the member open end 416) of the rear tine 419 is a raised projection 432 for engaging notches 423 and 424 of its cooperating member 411.

Intermediate of the ends 416 and 417 of each tread half 411 along its lower surface 415 there may be a web 433 connecting the tines 418, 419 and 420.

On the rear face 434 of the rearmost middle tine 420 there is a projection 435 to engage the surface 436 of the front tine rear notch 426 of each tread members cooperating partner. The projection 435 may be on a transverse line between the last of the series notches 423 and the long notch 424 in surface 422 of the front tine front recess 421.

I V-A 2R isers The risers 441) of the fourth form 400 of this invention are substantially identical with the risers 2% described in conjunction with the third form 180 of this invention.

Any differences in the risers 2013* and 440 which may be detected in the figures are results of design options exercised.

IV-B-TOP RISER SUB-ASSEMBLY FIGS. 24 and 25 show the basic elements of the top riser sub-assembly in exploded and partial assembly views. The top riser sub-assembly is comprised of a pair of top risers 441, a tread 410, a pair of top riser extensions 450, a pair of stand-off arms 470 and a spreader rung 480.

The top riser 441, used in the fourth form 400 of this invention, has a guide recess 236 along both edges 2134 and 295 at its outer face 202. Like top risers 2311, it has a notch 442 in each of the recesses 236 similar to notch 238 on risers 231 Also like top risers 230, the stub shaft 221 has a hole 233 drilled concentric with the shaft 221 with countersunk recesses 225 and 233 at its outer and inner ends respectively. In all other respects it may be identical to riser 230.

IV-B]T0p Riser Extensions The top riser extensions 451i serve the same purposes as are accomplished by top riser extensions 241 and 266, but in this case there is no need of left-hand and righthand castings, since a single casting 450 may be used on either side of the ladder 480.

The extensions 45% are planar in form and rectangular in configuration and have an inner surface 451, an outer surface 452, an upper end 453, a lower end 454, and edges 455; the extensions 450 are symmetrical about their longitudinal centerlines.

At its lower end 454, each of the extensions 450 are fitted with a bossed notch 456 identical to the configurations at the lower ends 263 of the risers 440 to accommodate the corresponding bossed notches 212 on the risers 441. Along the edges 455 and extending away from the outer face 452 of the extension 450 are flanges 457 spaced to straddle the body of the top risers 441 when the ladder 460 is assembled. Located opposite from each other along the flanges 457 and facing each other there may be locking tabs 458 to cooperate with notches 442 and. guide recesses 236 on top risers 441 when the stub shaft 221 of top riser 441 is at the uppermost limit of slot aperture 463.

Above the bossed notch 456 extending transversely of the extension 450 is a circularly arched aperture 459 in which a bolt 460 acts to hold a shouldered roller 461 against the inner face 451 of the extension. Slightly above the arched aperture 459 on the inner surface 451 at each edge 455 of the extension 450, a stand-off guide lug 462 stands out from the extension 450.

In the upper central portion of the extension 450' along the longitudinal centerline is a slot aperture 463 having -a recessed surface 464 surrounding the aperture 463 and opening to the extensions inner surface 451, similar tothe slot aperture in extensions 240 and 260.

In the upper end 453 of the extension 450 is a hanger bar 490 holding means 465 comprising: a hole 466 through the extension 450 having a countersunk recess 467 in the inner surface 451. On the outer surface 452 on either side of the hole 466 are a pair of hanger bar yokes 468 looped away from the extension outer surface 452 so that the hanger bar 490 may slide between the yokes 468 and the outer surface 452. A pair of guide surfaces 469 may run transversely of the extension 450 in conjunction with the yokes 468.

In this form 4420 of the ladder, the stand-01f arms 470 are of one piece construction rather than the multi-piece construction of stand-off mechanism 270 described as a part of the third form of this invention. Each standoff-arm 470 has a circular pivot portion 471 having fiat parallel sides 472 and a curved arm portion 473 extending away from the circular portion 471 to terminate in a shank 474 which may carry a rubber bearing foot 475.

The center of the circular portion 471 carries a hole 4'76 from side to side 472 of a diameter equalto the diameter of recess 233' on the top riser 441 stub shaft 221. On the convex edge 477 of the curved arm portion 473, intermediate of the ends of the arm 473, there is a notch 478 for bearing against the shouldered roller 461 bolted in slot 459 of the top riser extensions 450.

I V-B3Spreader Rung The spreader rung 481} of this form 400 of the ladder is identical to the rung 290 of the third form 180 except that the reduced diameter portion 292 at the ends 291 of the rung 2913 may be of different length than before.

IV-B4Assembly 0f the Sub-assembly The top sub-assembly of this form 4011 of the ladder is begun by mating two of the tread halves 411 into a tread 410 of the proper length. This is done by placing two of the tread half members 411 with their open ends 416 opposed to one another as shown in FIG. 30. The rear tines 419 of each member 411 should be under the forward flange 422 of the front tines 418 with the projections 432 against surface 422. As the members 411 are slid together the members 411 should be worked so that the middle tines 421 are not hung up on the webs 433. The sliding motion of the two halves 411 will be easy until the projections 432 reach the ends of the long notches 424 in front tine 418 surface 422. As the halves 411 are slid further and the projections 432 pass out of the notches 424 the motion is against the natural resilience of the tine couples 418'419 since the middle tines 420 are held against the Webs 433 if the halves 411 are maintained in the same plane. When the projection 432 is centered on surface 422 between the first of series notches 423 and the long notch 424, the ends of the front tines 418 will be against the projections 435 on the rear faces 434 of the rearmost middle tines 420. As sliding motion of the halves 411 continues, the projections 435 should be engaged with the surface 436 of the front tine 418 lower rear flange 436 (see FIG. 35). In such a condition the halves 411 are so interlocked that they resist bending moments that may be applied; this is apparent from FIG. 33. Further sliding motion of the interlocking halves 411 is accomplished against the friction and natural resilience of the members 411. For the top tread 410, the two halves '411 are forced together until the rear tine projections 432 are nested in the last of the series notches 423. (The series notches 423 are located at predetermined in- ,tervals to provide the various lengths of the treads 410 required in the ladders of this invention.)

Once the top, or shortest, tread 410 has been assembled, the top risers 441 and the top riser extensions are mated as described above in conjunction with the third form 180 of the ladder (also, see FIGS. 24, 25, 26, 27 and 28). FIG. 28 shows the interlocking of the top risers 441 and their extension 450 as the tabs 458 pass through notches 442 in the top risers 441. The notches 442 and the tabs 458 are so oriented that the risers 441 and extensions 459 may be mated only before the tread 410 is engaged and so that they will not come disengaged until the top tread 410 is removed when the ladder 400 is dismantled.

To complete the top sub-assembly, the mated top riser 441-extension 451} units are interlocked with the top tread 410 as described previously. The spreader rung 480 and the stand-off arms 470 are then installed across the upper part of the top sub-assembly between the recesses 233 of the top risers. The reduced diameter portions 292 at the ends 291 of the rung 480 are inserted into the holes 476 in the circular portions 471 of the arms 470 and then 23 into the recesses 233' to be secured by bolts 295 in holes 233 and in the tapped holes 294 in the rung 480. As the rung 480 and stand-offs 470* are installed, care must be taken that the curved ar-m portions 473 of the standoifs 470 lie between the stand-E guide lugs 462 and the shouldered rollers 461 on the extension inner sides 451. The top sub-assembly is then complete.

I IVC--ASSE1V1B LY OF THE LADDER 'Once the top riser sub-assembly has been completed, the remaining sliding sub-units may be built on to the base thus provided. The treads 410 are provided by interlocking pairs of the tread halves 411, but the halves should be assembled with the rear tine projections 432 stopped just short of the series notch 423 corresponding to the length of the tread 410 being assembled so that the tread 410 as first made up is longer than necessary (or as it appears in the finally assembled ladder). A pair of comrrnon or lower risers 440 are then interlocked with the lugs 193 at the closed ends 417 of the preliminarily interlocked tread halves 411 to provide a U-shaped group of elements. The flanged 223 stub shafts 221 on the risers 440 may be interlocked into sliding fit with the slot apertures 216 on the risers in the previously assembled portion of the ladder. Because the tread 4119 as first assembled is longer than it is in its finally assembled condition, the newly interlocked risers 440 pass over the guide tabs 206 at the lower. ends 203 of the immediately adjacent risers 440 in the already assembled part of the ladder rather than having to be forced past the guide tabs 206' against the normal resilience of the risers 440 as was required in the third embodiment 180 of the invention (see section Ill-C). When the newly interlocked risers 446 have been aligned with the previously assembled risers 44-0 or 441 and lie between the guide tabs 206 of the previously assembled risers 440 or 441, the tread 410 being added is then slid into its finally assembled position with the rear tine projections 432 in the proper front tine series notches 423.

Because of the natural resiliency of the interlocking tread halves 411 and because of the friction between them, the assembled tread halves 411 are prevented from coming apart, or even moving relative to one another, unless considerable force is applied longitudinally of the assembled halves 411. It can thus be seen that when the ladder is in use, since no force is applied in this manner, the tread cannot become elongated so that the risers 440 cannot become disengaged from their guide tabs 296 and the ladder maintains its desired rigidity and properly interlocked assembly in all in-use positions and conditions.

The major assembly of the ladder 400 may be completed by adding the rest of the risers 440 and treads 410 as described above.

IVDHANGER Bans Hanger bars 490 are adjustably fixed in the upper ends 453 of the top riser extensions 450. These hanger bars 490 are inserted within the yokes 468 against the extension outer surfaces 452 between the guide surfaces 469 therein. Each bar 490 has a longitudinal rectangular planar shank 491 which has a longitudinal slot 492 therein along its central portion. At one end of the shank 491 is a hanger hook means 390 (identical to that described above in conjunction with top riser extensions 240 and 260) having a body 301, lugs 302, a vertical edge 304, an upper edge 305, a top corner 306, a lower edge 307, and a lower inner corner 308, as described before. A bolt 493 may extend through the slot 492 in the shank 491 and through hole 466 in the top riser extensions 450 to be secured by a nut 494 in the recess 467 in the extension inner surface 451. By means of the bolt 493 and nut 494 combinations, the hanger bars 490 are adjustable in the top riser extensions 450. To receive the hanger hook means 300 of the hanger bars 490, hanger receptacles 310 (identical to those described above in section Ill-D) are provided which may be 24 afiixed to the surface upon which the ladder 400 is to be hung.

FIGS. 22 and 23 illustrate the ladder 401i attached to asmall boat 320. The ladder 400 is hung on the boat 320 as described above. As the ladder is lowered into its extended position and the rung 480 moves downward, the stand-offs 470 move against the rollers 462 in the extensions 450 and the rubber feet 475 move away from the ladder 400 until the rung 480 reaches its lowermost position, at which time the notches 478 on the convex edges 477 of the stand-off arms 473 cooperated with the rollers 462. The ladder 400 may then be supported at four points against the transom 321 of the boat. The remainder of the installation process has been described above. 7

The ladder 4&0 may also be installed along the top of the gunwale of the boat 320 with the stand-off feet 475 bearing against shell of the boat 320. When the ladder 490 is installed in such a manner, because of the doubly curved form of most boats now produced it is rare that the four bearing points of the ladder 400 will be in the same plane. If the gunwale and the shell of the boat 320 are curved, individual adjustment of the hanger hooks 300 and of the stand-oifs 470 is required. The individual adjustment of the hanger bars 490 has already been described; the adjustment of the stand-offs 470 is accomplished by moving the stand-off supporting shouldered rollers 461 in the arched slots 459 of the riser extensions 450. As the rollers 459 are moved, the footed ends 475 of the stand-oils 470 move up and down and to and from the ladder 409, but the notches 478 in the stand-offs 470 are always bearing on the rollers 461.

Because of the completely'adjustable four point suspension featured in this form 409 of the invention, the angle at which the ladder 400 is installed may be varied, and also the ladder may be installed against a surface which may range over a wide range away from vertical, both toward and away from the ladder.

While there is described above the principles of this invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of this invention.

What is claimed is:

1. A rigid telescoping top hung ladder comprising, as cast members: a plurality of planar tread units, and a plurality of equal length risers, said ladder comprised of a pair of said risers and one of said tread units arranged into U-shaped sections having said tread unit at the bottom thereof, the upper U-shaped sections nesting in the U-shaped section immediately therebelow; each of said risers including: a longitudinal slot aperture, tread engaging flange means at the lower end of said riser, and flanged stub-shaft projection means on said riser extending inwardly of said U-shaped section adjacent the upper end of said aperture; and spaced flange means on each U-shaped section extending laterally outwardly therefrom spanning the risers of the next section therebelow.

2. A ladder according to claim 1 wherein said tread unit is comprised of a pair of identical interlocking planar cast members, each member comprising: a closed end extending transversely thereof, a plurality of parallel tines extending to an open end opposite from said closed end, and a transverse web joining said tines intermediate of said closed end and said open end; said tines including: a front tine, a rear tine, and at least one middle tine, one of said tines including a series of notches therealong between said closed end and. said web, one of said tines including a projection at the end thereof; whereby said projection of one of said tines of one member of said pair is engaged with the notches of one of said tines of the other member of said'pair on engagement of said pair to form said tread unit; and whereby the engagement 25 of said projection in a notch of said series determines the overall length of said tread unit.

3. A ladder comprising:

(1) means at the upper end of said ladder for hanging said ladder, and

(II) a plurality of telescoping sections depending from said hanging means, each said section comprising:

(A) a tread member having I 1. a projection means at each end of said tread member (B) a pair of riser members, each having 1. a slot means extending longitudinally thereof 2. a flange means adjacent one end of said slot means for interlocking cooperation with said tread projection means, and

3. a pin means adjacent the other end of said slot means and located for interlocking sliding connection with said slot means in the riser of an adjacent supporting section of said ladder,

(C) means adjacent the ends of said tread member for guiding the pair of risers of the next adjacent depending section for sliding movement parallel to the pair of risers of the section having said guiding means.

4. A ladder according to claim 3 wherein said members of said sections are metal castings.

5. A ladder according to claims 3 wherein said tread member comprises a pair of identical extensible interlocking members each comprising a plurality of interfitting tines.

6. A ladder according to claim 5 wherein each of said interfitting tread members comprises a closed end extending transversely thereof, a plurality of parallel tines extending to an open end opposite from said closed end, and a transverse web joining said tines intermediate of said closed end and said open end.

7. A ladder according to claim 5 wherein said tines include a front tine, a rear tine and at least one middle tine, one of said tines including a series of notches therealong, and one of said tines including a toothed projection at the end thereof whereby said toothed projection of one of said tines of one member of said pair is engaged with the notches of one of said tines of the other member of said pair on engagement of said pair to form said tread member and whereby the engagement of said toothed projection in a notch of said series determines the overall length of said tread member.

8. A ladder according to claim 3 including means for separately manually assembling and disassembling each said section while maintaining interlocking sliding assembly of all of the remaining sections in all positions between their fully extended and fully compacted positions.

9. A ladder according to claim 3 wherein said hanger means includes extension means connected to the risers of the uppermost section of said ladder.

10. A ladder according to claim 9 wherein said extension means includes a slot means similar to said slot means in said riser members for cooperating with said pin means on said riser members of said upper ladder section depending from said extension means.

11. A ladder according to claim 10 wherein said extension means includes hook means for supporting said ladder along a wall, and wherein said hanger means includes a receptacle on said wall for receiving said hook means.

12. A ladder according to claim 11 including a retractable stand-off means connected to said ladder below said hook means for maintaining said ladder in a predetermined position relative to said wall.

13. A ladder according to claim 12 including means on said ladder for adjusting said stand-0E means for varying the position of said ladder to said wall.

14. A ladder according to claim 12 wherein said receptacle includes an inclined plane and a shoulder engaging said hook means to prevent disengagement of said hook means from said receptacle when said stand-oif means is in operation and said ladder is in its extended position.

15. A ladder according to claim 14 including means on said extension means for guiding and retracting said stand-off means by raising said depending section relative to said extension means, whereby said hook means can be disengaged from said receptacle.

. 16. A rigid collapsible ladder comprising:

(I) means at the upper end of said ladder for hanging said ladder adjacent a wall, and

(II) a plurality of telescoping upstanding U-shaped sections depending from said hanging means, each said section comprising:

(A) a planar tread member having:

1. a projection means at each end of said tread member,

(B) a pair of planar riser members, each having 1. a slot means extending longitudinally thereof 2. a flange and notched means adjacent one end of said slot means for interlocking cooperation with said tread projecting means, and

3. an integral inward-1y projecting and flanged stubshaft means adjacent the other end of said slot means and located for interlocking sliding connection with said slot means in the riser of an adjacent supporting section of said ladder,

(C) means adjacent the ends of said thread member for guiding and limiting the pair of risers of the next adjacent depending section to sliding movement parallel to the pair of risers of the section having said guiding means.

17. A ladder according to claim 16 wherein said slot includes flanges along its longitudinal edges for cooperation with said flanges on said stub shaft means.

18. A tread means for a ladder comprising a pair of identical interlocking members, each member having: a closed end extending transversely of said member from its front edge to its rear edge in the plane of said member, parallel tine finger elements extending from said closed end to a tine open end in the plane of said member, said finger elements including a front tine, a rear tine, and at least one middle tine, said rear tine being below said front and middle tines; one of said tines having a series of notches therealong; one of said times having a tine notch engaging projection at said open end of said memher; and a Web intermediate of said ends of said member along said lower surface connecting all said tine finger elements; whereby said pair of members may be positively interlocked by engaging said tine projections with said tine notches; wherein said series of notches determines the total effective length of said engaged pair of members.

19. A hanger hook and hook receptacle means, comprising: a planar hook body associated with a member to be hung, and a hook body receptacle means having an interiorly configured cavity; said hook body having a front edge, a top edge, a top corner at the intersection of said front and top edges, a lower edge substantially parallel to said front and top edges and having a lower corner opposite said top corner aross said hook body, a hook portion between said front edge and said lower edge, and a cylindrical lug perpendicular to said book portion on each side of said hook body; said hook receptacle having a T-shaped slot therein opening into said cavity through which said hanger book may be inserted into said receptacle, an inclined plane top hook corner abutting surface interiorly of said cavity adjacent the upper end of said slot, a cylindrical lower hook corner cooperating boss interiorly of said cavity adjacent the lower end of said slot,

associated therewith; while said: hook receptacle means.

maybe afiixedto any' surface between and inclusive of a vertical surface and: a horizontal surface.

20. A ladder having a hanger hook or hook receptacle according to claim 19 including means on said ladder for maintaining said: ladder substantially vertical to said surface.

21. A telescoping ladder comprising apiurality of step sections, eachsection comprising twoidentical risers and a tread connected together to form a U-shaped section with said tread across the bottom of the" U joining the twolower ends of said two risers; each said section comprising a: pair of outwardly extending flanges for guiding an adjacent lower section in telescoping relation thereto; each said riser comprising: a lower inwardly extending flange and notch for supporting and engaging the adjacent end of said tread, a longitudinal slot, and a slot engaging inwardly extending flanged projection at the opposite end of said slot from said inwardly extending flange, whereby said projection of an adjacent lower section is guided in the slot of an adjacent upper section during relative telescoping of said adjacent sectionsrand each said tread comprising a projection at each of its ends for engagement into said. notch in its adjacent riser.

22. A ladder according to claim 21 wherein said risers include said outwardly extending guiding flanges.

23. A ladder according to claim 21 including a pair of extensions connected to the top risers of the top section.

24. A ladder according to claim 23 wherein each of as said extensions comprises: a pair of outwardly extending flanges for guiding the adjacent lower section in telescopic relation thereto; and a longitudinal slot for cooperation with said projection on the riser of the adjacent lower section during relative telescoping of said adjacent lower section with said extension.

ReferencesCitcd' in the tile of this patent UNITED STATES PATENTS 426,180 Hammill Apr. 22, 1890 595,453 Fischer Dec. 14, 1897 933,816 Bartos et al. Sept. 14, 1909 1,029,768 Schneider June 18, 1912 1,063,048 McBain May 27, 1913 1,217,279 Coughtry Feb. 27, 1917 1,234,615 Bourdeau July 24, 1917 1,626,145 Mitchell Apr. 26, 1927 1,691,976 Kramer Nov. 20, 1928 1,841,676 Roberts Ian. 19, 1932 2,127,949 Zeman Aug. 23, 1938 2,182,475 Herline Dec. 5, 1939 2,194,856 Kostuk Mar. 26, 1940 2,390,000 Sampson Nov. 27, 1945 2,485,413. Ross Oct. 18, 1949 2,500,086 Mintus Mar. 7, 1950 2,798,653 Morrow July 9, 1957 2,888,305 Perry May 26, 1959 2,896,831 Ellingson- July 28, 1959 FOREIGN PATENTS 35,286 Sweden Aug. 6, 1913 

